Poor Sir Joshua Reynolds (or is it lucky Josh?). A selective collector, the painter acquired a work from the Duke of Leeds around 1790, it is thought in a swap for a Reynolds self-portrait. The painting Reynolds acquired seems to have been by an unattributed French painter, and it is thought may have been traced from Leonardo da Vinci's original of the 'Mona Lisa', no less, a century or so later than the period 1503-16 during which Leonardo painstakingly elaborated his original in thin layers of paint and varnish. Much discolouring occurred, even over a century. The copy appears to correspond to what the original Mona Lisa looked like. Reynolds must have been dismayed to be told by a Louvre curator that it was by no means the original, since it is of a very high standard. But back in 18th-century London, as many visitors to Reynolds may have thought it was a Leonardo as may not have realised that it couldn't be. In due course, Reynolds himself might have enjoyed the humorous aspect of seeing the reactions of socially and financially ambitious acquaintances, and even Royal Academicians (in a kind of slide test) may have been caught out, or kept in the dark.